A typical bipolar transistor comprises a vertical stack of layers of semiconductor material of alternating conduction type, i.e., NPN or PNP. Normally, the collector is located at the bottom of the stack with the base sandwiched between the collector and the emitter. Forward biasing the base to emitter junction causes current to flow through that junction. Current through the base to emitter junction causes a much larger current to flow between the collector and emitter.
Silicon Germanium (SiGe) heterojunction bipolar transistors (HBTs) have found widespread use in high speed applications and, especially in Radio Frequency (RF) applications, high speed wired data transmission, test equipment, and wireless applications. These transistors are commonly used in semiconductor devices for high-speed operation and large drive current applications. Such heterojunction bipolar transistors are increasingly being used for applications in extremely high frequency range technologies such as communications and satellite circuitry.
In advanced SiGe HBTs, as current density increases and devices are scaling down in size and geometry, electrical isolation and heat dissipation are becoming increasingly significant design considerations. Conventional isolation structures including deep trench (DT) and trench isolation (TI) are inadequate for transferring sufficient heat away from the HBT.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.